Persons enrolled in school were asked the year or grade in which enrolled up to 6 or more years of college. In 1960, enrollment was classified into four levels with separate years or grades identified within each level as indicated below. In 1970, enrollment is classified as in 1960 with the addition of nursery school.

Includes grades 1 through 8, identified separately in some tabulations. (Persons enrolled in a junior high school are classified as enrolled in elementary school or high school according to year in which enrolled.)

Includes 1 through 5 academic years and 6 years or more, identified separately in some tabulations. College enrollment is defined to include enrollment in junior or community colleges, regular 4-year colleges, and graduate or professional schools.

Includes persons attending schools controlled and supported mainly by religious organizations (parochial schools) or private persons or organizations. In 1970, parochial school enrollment and other private school enrollment are identified as separate categories for each level of school except college.